Re: [Xen-devel] FAILED/MISSING cstate/cpufreq/cpupower support with Xen 4.13 + kernel 5.4.14; withOUT xen/hypervisor, WORKS. bug or config?

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.01.2020 17:45, PGNet Dev wrote:
>> I'd like to request you adding the dom0 kernel boot parameters, too:
>> debug initcall_debug
> 
> added
> 
> with current config,
> 
>       [config.1]
>       options=dom0_max_vcpus=4 dom0_mem=4016M,max:4096M console_to_ring 
> conring_size=20480k loglvl=all guest_loglvl=all sync_console=true 
> iommu=verbose apic_verbosity=verbose sched=credit2 ucode=scan 
> intel_pstate=enable com1=115200,8n1 console=com1,vga
>       kernel=vmlinuz-5.5.0-24.g3f183bf-default root=/dev/mapper/VG0-ROOT 
> rd.shell systemd.log_target=kmsg systemd.log_level=info showopts noquiet 
> print_fatal_signals=1 log_buf_len=20M printk.devkmsg=on earlyprintk=xen,keep 
> debug loglevel=8 lapic=debug apic_verbosity=debug apic=debug sched_debug 
> initcall_debug root=/dev/mapper/VG0-ROOT rootfstype=ext4 
> rootflags=journal_checksum noresume audit=0 modeset=1 nouveau.modeset=1 
> fsck.mode=auto fsck.repair=preen net.ifnames=1 biosdevname=0 
> scsi_mod.use_blk_mq=1 mce=bootlog console=hvc0 intel_pstate=force
>       ramdisk=initrd-5.5.0-24.g3f183bf-default
> 
> as before -- no cpupower frequency-info data, xenpm reports scaling_driver == 
> acpi=cpufreq
> 
> log below
> 
> NOTE the "(XEN) parameter "intel_pstate" unknown!" ... that's clearly not a 
> good sign.

Of course. There's no such command line option in Xen.

>> So I wonder what exactly you mean by saying "still seeing NO cpufreq/scaling 
>> info
> 
> this
> 
>       cpupower frequency-info
>               analyzing CPU 0:
>                 no or unknown cpufreq driver is active on this CPU
>                 CPUs which run at the same hardware frequency: Not Available
>                 CPUs which need to have their frequency coordinated by 
> software: Not Available
>                 maximum transition latency:  Cannot determine or is not 
> supported.
>               Not Available
>                 available cpufreq governors: Not Available
>                 Unable to determine current policy
>                 current CPU frequency: Unable to call hardware
>                 current CPU frequency:  Unable to call to kernel
>                 boost state support:
>                   Supported: no
>                   Active: no
> 
> cpupower reports no freq mgmt
> xenpm does
> 
> not clear 2 me if that's expected.

As said (I think more than once) before - xenpm is the only reliable
information source. For other user space tools you'd first need to
figure out whether they're Xen-aware; most would merely try to
interface with the (Dom0) kernel, yet this - as also said before -
won't help, as the kernel is unaware of what is going on. Please can
we focus on the Xen aspects here (including Xen-specific Linux parts
and the tools provided alongside Xen)? The question isn't what
random tools report. The question is whether P- and C-state
management actually (don't) work on your system. For this, relevant
parts of Xen and Dom0 logs may be necessary, and/or xenpm output.

Jan

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